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Iwata K, Ferdousi F, Arai Y, Isoda H. Modulation of mitochondrial activity by sugarcane (Saccharum officinarum L.) top extract and its bioactive polyphenols: a comprehensive transcriptomics analysis in C2C12 myotubes and HepG2 hepatocytes. NATURAL PRODUCTS AND BIOPROSPECTING 2024; 14:2. [PMID: 38177614 PMCID: PMC10766937 DOI: 10.1007/s13659-023-00423-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 11/27/2023] [Indexed: 01/06/2024]
Abstract
Age-related mitochondrial dysfunction leads to defects in cellular energy metabolism and oxidative stress defense systems, which can contribute to tissue damage and disease development. Among the key regulators responsible for mitochondrial quality control, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is an important target for mitochondrial dysfunction. We have previously reported that bioactive polyphenols extracted from sugarcane top (ST) ethanol extract (STEE) could activate neuronal energy metabolism and increase astrocyte PGC-1α transcript levels. However, their potential impact on the mitochondria activity in muscle and liver cells has not yet been investigated. To address this gap, our current study examined the effects of STEE and its polyphenols on cultured myotubes and hepatocytes in vitro. Rhodamine 123 assay revealed that the treatment with STEE and its polyphenols resulted in an increase in mitochondrial membrane potential in C2C12 myotubes. Furthermore, a comprehensive examination of gene expression patterns through transcriptome-wide microarray analysis indicated that STEE altered gene expressions related to mitochondrial functions, fatty acid metabolism, inflammatory cytokines, mitogen-activated protein kinase (MAPK) signaling, and cAMP signaling in both C2C12 myotubes and HepG2 hepatocytes. Additionally, protein-protein interaction analysis identified the PGC-1α interactive-transcription factors-targeted regulatory network of the genes regulated by STEE, and the quantitative polymerase chain reaction results confirmed that STEE and its polyphenols upregulated the transcript levels of PGC-1α in both C2C12 and HepG2 cells. These findings collectively suggest the potential beneficial effects of STEE on muscle and liver tissues and offer novel insights into the potential nutraceutical applications of this material.
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Affiliation(s)
- Kengo Iwata
- Alliance for Research on the Mediterranean and North Africa (ARENA), University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
- Nippo Co., Ltd., Daito, Osaka, 574-0062, Japan
| | - Farhana Ferdousi
- Alliance for Research on the Mediterranean and North Africa (ARENA), University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
- Institute of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | | | - Hiroko Isoda
- Alliance for Research on the Mediterranean and North Africa (ARENA), University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.
- Institute of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.
- AIST-University of Tsukuba Open Innovation Laboratory for Food and Medicinal Resource Engineering (FoodMed-OIL), Tsukuba, Ibaraki, 305-8572, Japan.
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Mao P, Huang C, Li Y, Zhao Y, Zhou S, Zhao Z, Mu Y, Wang L, Li F, Zhao AZ. Pharmacological targeting of type phosphodiesterase 4 inhibits the development of acute myeloid leukemia by impairing mitochondrial function through the Wnt/β-catenin pathway. Biomed Pharmacother 2023; 157:114027. [PMID: 36436494 DOI: 10.1016/j.biopha.2022.114027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/09/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022] Open
Abstract
Acute myeloid leukemia (AML) is prone to drug-resistant relapse with a low 5-year survival rate. New therapeutic modalities are sorely needed to provide hope for AML relapse patients. Herein, we demonstrated a specific inhibitor of type 4 phosphodiesterase (PDE4), Zl-n-91, could significantly reduce the proliferation of AML cells, block DNA replication process, and increase AML cell death. Zl-n-91 also impeded the growth of subcutaneous xenograft and prolonged the survival of the MLL-AF9-driven AML model. Bioinformatic analysis revealed that elevated mitochondrial gene signatures inversely correlate with the survival of AML patients; and importantly, Zl-n-91 strongly suppressed the function of mitochondria. In addition, this PDE4 inhibitor induced alterations in multiple signaling pathways, including the reduction of β-catenin activity. Stimulation of the Wnt/β-catenin pathway could attenuate the inhibitory effect of Zl-n-91 on AML cell proliferation as well as mitochondrial function. Taken together, we revealed for the first time that targeting PDE4 activity could attenuate mitochondrial function through a Wnt/β-catenin pathway, which in turn would block the growth of AML cells. Specific PDE4 inhibitors can potentially serve as a new treatment modality for AML patients.
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Affiliation(s)
- Ping Mao
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Changhao Huang
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Yuyu Li
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Yuanyi Zhao
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Sujin Zhou
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Zhenggang Zhao
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Yunping Mu
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Lina Wang
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China
| | - Fanghong Li
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China.
| | - Allan Z Zhao
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Xiaoguwei Street, Panyu District, Guangzhou, Guangdong 510006, China.
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Staples JF, Mathers KE, Duffy BM. Mitochondrial Metabolism in Hibernation: Regulation and Implications. Physiology (Bethesda) 2022; 37:0. [PMID: 35658625 DOI: 10.1152/physiol.00006.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Hibernators rapidly and reversibly suppress mitochondrial respiration and whole animal metabolism. Posttranslational modifications likely regulate these mitochondrial changes, which may help conserve energy in winter. These modifications are affected by reactive oxygen species (ROS), so suppressing mitochondrial ROS production may also be important for hibernators, just as it is important for surviving ischemia-reperfusion injury.
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Affiliation(s)
- James F Staples
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | - Katherine E Mathers
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | - Brynne M Duffy
- Department of Biology, University of Western Ontario, London, Ontario, Canada
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4
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Abstract
The field of cAMP signaling is witnessing exciting developments with the recognition that cAMP is compartmentalized and that spatial regulation of cAMP is critical for faithful signal coding. This realization has changed our understanding of cAMP signaling from a model in which cAMP connects a receptor at the plasma membrane to an intracellular effector in a linear pathway to a model in which cAMP signals propagate within a complex network of alternative branches and the specific functional outcome strictly depends on local regulation of cAMP levels and on selective activation of a limited number of branches within the network. In this review, we cover some of the early studies and summarize more recent evidence supporting the model of compartmentalized cAMP signaling, and we discuss how this knowledge is starting to provide original mechanistic insight into cell physiology and a novel framework for the identification of disease mechanisms that potentially opens new avenues for therapeutic interventions. SIGNIFICANCE STATEMENT: cAMP mediates the intracellular response to multiple hormones and neurotransmitters. Signal fidelity and accurate coordination of a plethora of different cellular functions is achieved via organization of multiprotein signalosomes and cAMP compartmentalization in subcellular nanodomains. Defining the organization and regulation of subcellular cAMP nanocompartments is necessary if we want to understand the complex functional ramifications of pharmacological treatments that target G protein-coupled receptors and for generating a blueprint that can be used to develop precision medicine interventions.
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Affiliation(s)
- Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Anna Zerio
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Miguel J Lobo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Di Benedetto G, Lefkimmiatis K, Pozzan T. The basics of mitochondrial cAMP signalling: Where, when, why. Cell Calcium 2020; 93:102320. [PMID: 33296837 DOI: 10.1016/j.ceca.2020.102320] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/16/2020] [Accepted: 11/16/2020] [Indexed: 12/15/2022]
Abstract
Cytosolic cAMP signalling in live cells has been extensively investigated in the past, while only in the last decade the existence of an intramitochondrial autonomous cAMP homeostatic system began to emerge. Thanks to the development of novel tools to investigate cAMP dynamics and cAMP/PKA-dependent phosphorylation within the matrix and in other mitochondrial compartments, it is now possible to address directly and in intact living cells a series of questions that until now could be addressed only by indirect approaches, in isolated organelles or through subcellular fractionation studies. In this contribution we discuss the mechanisms that regulate cAMP dynamics at the surface and inside mitochondria, and its crosstalk with organelle Ca2+ handling. We then address a series of still unsolved questions, such as the intramitochondrial localization of key elements of the cAMP signaling toolkit, e.g., adenylate cyclases, phosphodiesterases, protein kinase A (PKA) and Epac. Finally, we discuss the evidence for and against the existence of an intramitochondrial PKA pool and the functional role of cAMP increases within the organelle matrix.
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Affiliation(s)
- Giulietta Di Benedetto
- Neuroscience Institute, National Research Council of Italy (CNR), 35121 Padova, Italy; Veneto Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, 35129 Padova, Italy.
| | - Konstantinos Lefkimmiatis
- Veneto Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, 35129 Padova, Italy; Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
| | - Tullio Pozzan
- Neuroscience Institute, National Research Council of Italy (CNR), 35121 Padova, Italy; Veneto Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy
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An improved method for isolation of mitochondria from cell lines that enables reconstitution of calcium-dependent processes. Anal Biochem 2019; 577:52-58. [PMID: 31022379 DOI: 10.1016/j.ab.2019.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/11/2019] [Accepted: 04/16/2019] [Indexed: 01/15/2023]
Abstract
Optimum cytosolic calcium concentrations support balanced mitochondrial respiration. However, cytosolic Ca2+ concentrations vary among cell types and excess Ca2+ can cause mitochondrial dysfunction. We optimized an isolation protocol to eliminate excess Ca2+ and thereby minimizing structural damage. Ca2+ uptake was monitored by measuring mitochondrial Ca2+-dependent PKA activity using cAMP ELISAs, and O2 consumption levels during mitochondrial respiration using high-resolution respirometry. 3 nM Ca2+ was found to increase cAMP levels and produce optimal state III respiration. Hence, optimized isolation of mitochondria from cell lines using calcium denudation provides the best platform for the study of Ca2+-dependent regulation of mitochondrial signaling.
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Bouchez C, Devin A. Mitochondrial Biogenesis and Mitochondrial Reactive Oxygen Species (ROS): A Complex Relationship Regulated by the cAMP/PKA Signaling Pathway. Cells 2019; 8:cells8040287. [PMID: 30934711 PMCID: PMC6523352 DOI: 10.3390/cells8040287] [Citation(s) in RCA: 146] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/15/2019] [Accepted: 03/20/2019] [Indexed: 12/23/2022] Open
Abstract
Mitochondrial biogenesis is a complex process. It requires the contribution of both the nuclear and the mitochondrial genomes and therefore cross talk between the nucleus and mitochondria. Cellular energy demand can vary by great length and it is now well known that one way to adjust adenosine triphosphate (ATP) synthesis to energy demand is through modulation of mitochondrial content in eukaryotes. The knowledge of actors and signals regulating mitochondrial biogenesis is thus of high importance. Here, we review the regulation of mitochondrial biogenesis both in yeast and in mammalian cells through mitochondrial reactive oxygen species.
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Affiliation(s)
- Cyrielle Bouchez
- Université Bordeaux, IBGC, UMR 5095, 33077 Bordeaux cedex, France.
- Institut de Biochimie et Génétique Cellulaires, CNRS UMR 5095, 1, rue Camille Saint Saëns, 33077 Bordeaux Cedex, France.
| | - Anne Devin
- Université Bordeaux, IBGC, UMR 5095, 33077 Bordeaux cedex, France.
- Institut de Biochimie et Génétique Cellulaires, CNRS UMR 5095, 1, rue Camille Saint Saëns, 33077 Bordeaux Cedex, France.
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Spät A, Szanda G. Mitochondrial cAMP and Ca 2+ metabolism in adrenocortical cells. Pflugers Arch 2018; 470:1141-1148. [PMID: 29876637 DOI: 10.1007/s00424-018-2157-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/14/2018] [Accepted: 05/17/2018] [Indexed: 01/22/2023]
Abstract
The biological effects of physiological stimuli of adrenocortical glomerulosa cells are predominantly mediated by the Ca2+ and the cAMP signal transduction pathways. The complex interplay between these signalling systems fine-tunes aldosterone secretion. In addition to the well-known cytosolic interactions, a novel intramitochondrial Ca2+-cAMP interplay has been recently recognised. The cytosolic Ca2+ signal is rapidly transferred into the mitochondrial matrix where it activates Ca2+-sensitive dehydrogenases, thus enhancing the formation of NADPH, a cofactor of steroid synthesis. Quite a few cell types, including H295R adrenocortical cells, express the soluble adenylyl cyclase within the mitochondria and the elevation of mitochondrial [Ca2+] activates the enzyme, thus resulting in the Ca2+-dependent formation of cAMP within the mitochondrial matrix. On the other hand, mitochondrial cAMP (mt-cAMP) potentiates the transfer of cytosolic Ca2+ into the mitochondrial matrix. This cAMP-mediated positive feedback control of mitochondrial Ca2+ uptake may facilitate the rapid hormonal response to emergency situations since knockdown of soluble adenylyl cyclase attenuates aldosterone production whereas overexpression of the enzyme facilitates steroidogenesis in vitro. Moreover, the mitochondrial Ca2+-mt-cAMP-Ca2+ uptake feedback loop is not a unique feature of adrenocortical cells; a similar signalling system has been described in HeLa cells as well.
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Affiliation(s)
- András Spät
- Department of Physiology, Semmelweis University Medical School, POB 2, Budapest, 1428, Hungary.
- MTA-SE Laboratory of Molecular Physiology, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary.
| | - Gergő Szanda
- Department of Physiology, Semmelweis University Medical School, POB 2, Budapest, 1428, Hungary
- MTA-SE Laboratory of Molecular Physiology, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary
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9
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Szanda G, Wisniewski É, Rajki A, Spät A. Mitochondrial cAMP exerts positive feedback on mitochondrial Ca 2+ uptake via the recruitment of Epac1. J Cell Sci 2018; 131:jcs.215178. [PMID: 29661848 DOI: 10.1242/jcs.215178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/07/2018] [Indexed: 01/10/2023] Open
Abstract
We have previously demonstrated in H295R adrenocortical cells that the Ca2+-dependent production of mitochondrial cAMP (mt-cAMP) by the matrix soluble adenylyl cyclase (sAC; encoded by ADCY10) is associated with enhanced aldosterone production. Here, we examined whether mitochondrial sAC and mt-cAMP fine tune mitochondrial Ca2+ metabolism to support steroidogenesis. Reduction of mt-cAMP formation resulted in decelerated mitochondrial Ca2+ accumulation in intact cells during K+-induced Ca2+ signalling and also in permeabilized cells exposed to elevated perimitochondrial [Ca2+]. By contrast, treatment with the membrane-permeable cAMP analogue 8-Br-cAMP, inhibition of phosphodiesterase 2 and overexpression of sAC in the mitochondrial matrix all intensified Ca2+ uptake into the organelle. Identical mt-cAMP dependence of mitochondrial Ca2+ uptake was also observed in HeLa cells. Importantly, the enhancing effect of mt-cAMP on Ca2+ uptake was independent from both the mitochondrial membrane potential and Ca2+ efflux, but was reduced by Epac1 (also known as RAPGEF3) blockade both in intact and in permeabilized cells. Finally, overexpression of sAC in the mitochondrial matrix potentiated aldosterone production implying that the observed positive feedback mechanism of mt-cAMP on mitochondrial Ca2+ accumulation may have a role in the rapid initiation of steroidogenesis.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Gergő Szanda
- Department of Physiology, Semmelweis University Medical School, 1482 POB 2 Budapest, Hungary .,MTA-SE Laboratory of Molecular Physiology, Semmelweis University and Hungarian Academy of Sciences, 1482 POB 2 Budapest, Hungary
| | - Éva Wisniewski
- Department of Physiology, Semmelweis University Medical School, 1482 POB 2 Budapest, Hungary
| | - Anikó Rajki
- MTA-SE Laboratory of Molecular Physiology, Semmelweis University and Hungarian Academy of Sciences, 1482 POB 2 Budapest, Hungary
| | - András Spät
- Department of Physiology, Semmelweis University Medical School, 1482 POB 2 Budapest, Hungary .,MTA-SE Laboratory of Molecular Physiology, Semmelweis University and Hungarian Academy of Sciences, 1482 POB 2 Budapest, Hungary
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Zhang F, Zhang L, Qi Y, Xu H. Mitochondrial cAMP signaling. Cell Mol Life Sci 2016; 73:4577-4590. [PMID: 27233501 PMCID: PMC5097110 DOI: 10.1007/s00018-016-2282-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/25/2016] [Accepted: 05/20/2016] [Indexed: 12/19/2022]
Abstract
Cyclic adenosine 3, 5'-monophosphate (cAMP) is a ubiquitous second messenger regulating many biological processes, such as cell migration, differentiation, proliferation and apoptosis. cAMP signaling functions not only on the plasma membrane, but also in the nucleus and in organelles such as mitochondria. Mitochondrial cAMP signaling is an indispensable part of the cytoplasm-mitochondrion crosstalk that maintains mitochondrial homeostasis, regulates mitochondrial dynamics, and modulates cellular stress responses and other signaling pathways. Recently, the compartmentalization of mitochondrial cAMP signaling has attracted great attentions. This new input should be carefully taken into account when we interpret the findings of mitochondrial cAMP signaling. In this review, we summarize previous and recent progress in our understanding of mitochondrial cAMP signaling, including the components of the signaling cascade, and the function and regulation of this signaling pathway in different mitochondrial compartments.
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Affiliation(s)
- Fan Zhang
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Liping Zhang
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yun Qi
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Hong Xu
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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Regulation of mitochondrial functions by protein phosphorylation and dephosphorylation. Cell Biosci 2016; 6:25. [PMID: 27087918 PMCID: PMC4832502 DOI: 10.1186/s13578-016-0089-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/01/2016] [Indexed: 12/02/2022] Open
Abstract
The mitochondria are double membrane-bound organelles found in most eukaryotic cells. They generate most of the cell’s energy supply of adenosine triphosphate (ATP). Protein phosphorylation and dephosphorylation are critical mechanisms in the regulation of cell signaling networks and are essential for almost all the cellular functions. For many decades, mitochondria were considered autonomous organelles merely functioning to generate energy for cells to survive and proliferate, and were thought to be independent of the cellular signaling networks. Consequently, phosphorylation and dephosphorylation processes of mitochondrial kinases and phosphatases were largely neglected. However, evidence accumulated in recent years on mitochondria-localized kinases/phosphatases has changed this longstanding view. Mitochondria are increasingly recognized as a hub for cell signaling, and many kinases and phosphatases have been reported to localize in mitochondria and play important functions. However, the strength of the evidence on mitochondrial localization and the activities of the reported kinases and phosphatases vary greatly, and the detailed mechanisms on how these kinases/phosphatases translocate to mitochondria, their subsequent function, and the physiological and pathological implications of their localization are still poorly understood. Here, we provide an updated perspective on the recent advancement in this area, with an emphasis on the implications of mitochondrial kinases/phosphatases in cancer and several other diseases.
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Abstract
Many environmental conditions can constrain the ability of animals to obtain sufficient food energy, or transform that food energy into useful chemical forms. To survive extended periods under such conditions animals must suppress metabolic rate to conserve energy, water, or oxygen. Amongst small endotherms, this metabolic suppression is accompanied by and, in some cases, facilitated by a decrease in core body temperature-hibernation or daily torpor-though significant metabolic suppression can be achieved even with only modest cooling. Within some ectotherms, winter metabolic suppression exceeds the passive effects of cooling. During dry seasons, estivating ectotherms can reduce metabolism without changes in body temperature, conserving energy reserves, and reducing gas exchange and its inevitable loss of water vapor. This overview explores the similarities and differences of metabolic suppression among these states within adult animals (excluding developmental diapause), and integrates levels of organization from the whole animal to the genome, where possible. Several similarities among these states are highlighted, including patterns and regulation of metabolic balance, fuel use, and mitochondrial metabolism. Differences among models are also apparent, particularly in whether the metabolic suppression is intrinsic to the tissue or depends on the whole-animal response. While in these hypometabolic states, tissues from many animals are tolerant of hypoxia/anoxia, ischemia/reperfusion, and disuse. These natural models may, therefore, serve as valuable and instructive models for biomedical research.
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Affiliation(s)
- James F Staples
- Department of Biology, University of Western Ontario, London, Ontario, Canada
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Staples JF. Metabolic suppression in mammalian hibernation: the role of mitochondria. ACTA ACUST UNITED AC 2015; 217:2032-6. [PMID: 24920833 DOI: 10.1242/jeb.092973] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hibernation evolved in some small mammals that live in cold environments, presumably to conserve energy when food supplies are low. Throughout the winter, hibernators cycle spontaneously between torpor, with low metabolism and near-freezing body temperatures, and euthermia, with high metabolism and body temperatures near 37°C. Understanding the mechanisms underlying this natural model of extreme metabolic plasticity is important for fundamental and applied science. During entrance into torpor, reductions in metabolic rate begin before body temperatures fall, even when thermogenesis is not active, suggesting active mechanisms of metabolic suppression, rather than passive thermal effects. Mitochondrial respiration is suppressed during torpor, especially when measured in liver mitochondria fuelled with succinate at 37°C in vitro. This suppression of mitochondrial metabolism appears to be invoked quickly during entrance into torpor when body temperature is high, but is reversed slowly during arousal when body temperature is low. This pattern may reflect body temperature-sensitive, enzyme-mediated post-translational modifications of oxidative phosphorylation complexes, for instance by phosphorylation or acetylation.
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Affiliation(s)
- James F Staples
- Department of Biology, University of Western Ontario, London, ON, Canada, N6A 5B8
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Lefkimmiatis K, Zaccolo M. cAMP signaling in subcellular compartments. Pharmacol Ther 2014; 143:295-304. [PMID: 24704321 PMCID: PMC4117810 DOI: 10.1016/j.pharmthera.2014.03.008] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 01/11/2023]
Abstract
In the complex microcosm of a cell, information security and its faithful transmission are critical for maintaining internal stability. To achieve a coordinated response of all its parts to any stimulus the cell must protect the information received from potentially confounding signals. Physical segregation of the information transmission chain ensures that only the entities able to perform the encoded task have access to the relevant information. The cAMP intracellular signaling pathway is an important system for signal transmission responsible for the ancestral 'flight or fight' response and involved in the control of critical functions including frequency and strength of heart contraction, energy metabolism and gene transcription. It is becoming increasingly apparent that the cAMP signaling pathway uses compartmentalization as a strategy for coordinating the large number of key cellular functions under its control. Spatial confinement allows the formation of cAMP signaling "hot spots" at discrete subcellular domains in response to specific stimuli, bringing the information in proximity to the relevant effectors and their recipients, thus achieving specificity of action. In this report we discuss how the different constituents of the cAMP pathway are targeted and participate in the formation of cAMP compartmentalized signaling events. We illustrate a few examples of localized cAMP signaling, with a particular focus on the nucleus, the sarcoplasmic reticulum and the mitochondria. Finally, we discuss the therapeutic potential of interventions designed to perturb specific cAMP cascades locally.
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Affiliation(s)
| | - Manuela Zaccolo
- Department Of Physiology, Anatomy & Genetics, University of Oxford, UK.
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Gomez-Chang E, Espinosa-Garcia MT, Olvera-Sanchez S, Flores-Herrera O, Martinez F. PKA tightly bound to human placental mitochondria participates in steroidogenesis and is not modified by cAMP. Placenta 2014; 35:748-62. [PMID: 25012296 DOI: 10.1016/j.placenta.2014.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 06/10/2014] [Accepted: 06/12/2014] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Protein phosphorylation plays an important role in the modulation of steroidogenesis and it depends on the activation of different signaling cascades. Previous data showed that PKA activity is related to steroidogenesis in mitochondria from syncytiotrophoblast of human placenta (HPM). PKA localization and contribution in progesterone synthesis and protein phosphorylation of HPM was assessed in this work. METHODS Placental mitochondria and submitochondrial fractions were used. Catalytic and regulatory PKA subunits were identified by Western blot. PKA activity was determined by the incorporation of (32)P into proteins in the presence or absence of specific inhibitors. The effect of PKA activators and inhibitors on steroidogenesis and protein phosphorylation in HPM was tested by radioimmunoassay and autoradiography. RESULTS The PKAα catalytic subunit was distributed in all the submitochondrial fractions whereas βII regulatory subunit was the main isoform observed in both the outer and inner membranes of HPM. PKA located in the inner membrane showed the highest activity. Progesterone synthesis and mitochondrial protein phosphorylation are modified by inhibitors of PKA catalytic subunit but are neither sensitive to inhibitors of the regulatory subunit nor to activators of the holoenzyme. DISCUSSION The lack of response in the presence of PKA activators and inhibitors of the regulatory subunit suggests that the activation of intramitochondrial PKA cannot be prevented or further activated. CONCLUSIONS The phosphorylating activity of PKA inside HPM could be an important component of the steroidogenesis transduction cascade, probably exerting its effects by direct phosphorylation of its substrates or by modulating other kinases and phosphatases.
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Affiliation(s)
- E Gomez-Chang
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - M T Espinosa-Garcia
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - S Olvera-Sanchez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - O Flores-Herrera
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - F Martinez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico.
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Valsecchi F, Konrad C, Manfredi G. Role of soluble adenylyl cyclase in mitochondria. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2555-60. [PMID: 24907564 DOI: 10.1016/j.bbadis.2014.05.035] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/19/2014] [Accepted: 05/28/2014] [Indexed: 11/25/2022]
Abstract
The soluble adenylyl cyclase (sAC) catalyzes the conversion of ATP into cyclic AMP (cAMP). Recent studies have shed new light on the role of sAC localized in mitochondria and its product cAMP, which drives mitochondrial protein phosphorylation and regulation of the oxidative phosphorylation system and other metabolic enzymes, presumably through the activation of intra-mitochondrial PKA. In this review article, we summarize recent findings on mitochondrial sAC activation by bicarbonate (HCO(3)(-)) and calcium (Ca²⁺) and the effects on mitochondrial metabolism. We also discuss putative mechanisms whereby sAC-mediated mitochondrial protein phosphorylation regulates mitochondrial metabolism. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- Federica Valsecchi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Csaba Konrad
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Giovanni Manfredi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA.
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17
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Abstract
Heart failure (HF) is a complex chronic clinical syndrome. Energy deficit is considered to be a key contributor to the development of both cardiac and skeletal myopathy. In HF, several components of cardiac and skeletal muscle bioenergetics are altered, such as oxygen availability, substrate oxidation, mitochondrial ATP production, and ATP transfer to the contractile apparatus via the creatine kinase shuttle. This review focuses on alterations in mitochondrial biogenesis and respirasome organization, substrate oxidation coupled with ATP synthesis in the context of their contribution to the chronic energy deficit, and mechanical dysfunction of the cardiac and skeletal muscle in HF. We conclude that HF is associated with decreased mitochondrial biogenesis and function in both heart and skeletal muscle, supporting the concept of a systemic mitochondrial cytopathy. The sites of mitochondrial defects are located within the electron transport and phosphorylation apparatus and differ with the etiology and progression of HF in the two mitochondrial populations (subsarcolemmal and interfibrillar) of cardiac and skeletal muscle. The roles of adrenergic stimulation, the renin-angiotensin system, and cytokines are evaluated as factors responsible for the systemic energy deficit. We propose a cyclic AMP-mediated mechanism by which increased adrenergic stimulation contributes to the mitochondrial dysfunction.
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Candas D, Li JJ. MnSOD in oxidative stress response-potential regulation via mitochondrial protein influx. Antioxid Redox Signal 2014; 20:1599-617. [PMID: 23581847 PMCID: PMC3942709 DOI: 10.1089/ars.2013.5305] [Citation(s) in RCA: 473] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE The mitochondrial antioxidant manganese superoxide dismutase (MnSOD) is encoded by genomic DNA and its dismutase function is fully activated in the mitochondria to detoxify free radical O2(•-) generated by mitochondrial respiration. Accumulating evidence shows an extensive communication between the mitochondria and cytoplasm under oxidative stress. Not only is the MnSOD gene upregulated by oxidative stress, but MnSOD activity can be enhanced via the mitochondrial protein influx (MPI). RECENT ADVANCES A cluster of MPI containing cytoplasmic/nuclear proteins, such as cyclins, cyclin-dependent kinases, and p53 interact with and alter MnSOD activity. These proteins modulate MnSOD superoxide scavenging activity via post-translational modifications in the mitochondria. In addition to well-established pathways in gene expression, recent findings suggest that MnSOD enzymatic activity can also be enhanced by phosphorylation of specific motifs in mitochondria. This review attempts to discuss the pre- and post-translational regulation of MnSOD, and how these modifications alter MnSOD activity, which induces a cell adaptive response to oxidative stress. CRITICAL ISSUES MnSOD is biologically significant to aerobic cells. Its role in protecting the cells against the deleterious effects of reactive oxygen species is evident. However, the exact network of MnSOD-associated cellular adaptive reaction to oxidative stress and its post-translational modifications, especially its enzymatic enhancement via phosphorylation, is not yet fully understood. FUTURE DIRECTIONS The broad discussion of the multiple aspects of MnSOD regulation, including gene expression, protein modifications, and enzymatic activity, will shed light onto the unknown mechanisms that govern the prosurvival networks involved in cellular and mitochondrial adaptive response to genotoxic environment.
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Affiliation(s)
- Demet Candas
- 1 Department of Radiation Oncology, University of California Davis , Sacramento, California
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Huang H, Wang H, Figueiredo-Pereira ME. Regulating the ubiquitin/proteasome pathway via cAMP-signaling: neuroprotective potential. Cell Biochem Biophys 2014; 67:55-66. [PMID: 23686612 DOI: 10.1007/s12013-013-9628-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The cAMP-signaling pathway has been under intensive investigation for decades. It is a wonder that such a small simple molecule like cAMP can modulate a vast number of diverse processes in different types of cells. The ubiquitous involvement of cAMP-signaling in a variety of cellular events requires tight spatial and temporal control of its generation, propagation, compartmentalization, and elimination. Among the various steps of the cAMP-signaling pathway, G-protein-coupled receptors, adenylate cyclases, phosphodiesterases, the two major cAMP targets, i.e., protein kinase A and exchange protein activated by cAMP, as well as the A-kinase anchoring proteins, are potential targets for drug development. Herein we review the recent progress on the regulation and manipulation of different steps of the cAMP-signaling pathway. We end by focusing on the emerging role of cAMP-signaling in modulating protein degradation via the ubiquitin/proteasome pathway. New discoveries on the regulation of the ubiquitin/proteasome pathway by cAMP-signaling support the development of new therapeutic approaches to prevent proteotoxicity in chronic neurodegenerative disorders and other human disease conditions associated with impaired protein turnover by the ubiquitin/proteasome pathway and the accumulation of ubiquitin-protein aggregates.
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Affiliation(s)
- He Huang
- Department of Biological Sciences, Hunter College and Graduate Center, City University of New York, 695 Park Avenue, New York, NY 10065, USA
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20
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Potential role of subunit c of F0F1-ATPase and subunit c of storage body in the mitochondrial permeability transition. Effect of the phosphorylation status of subunit c on pore opening. Cell Calcium 2014; 55:69-77. [DOI: 10.1016/j.ceca.2013.12.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/25/2013] [Accepted: 12/08/2013] [Indexed: 01/27/2023]
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Oxidative stress induced mitochondrial protein kinase A mediates cytochrome c oxidase dysfunction. PLoS One 2013; 8:e77129. [PMID: 24130844 PMCID: PMC3795003 DOI: 10.1371/journal.pone.0077129] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/29/2013] [Indexed: 11/30/2022] Open
Abstract
Previously we showed that Protein kinase A (PKA) activated in hypoxia and myocardial ischemia/reperfusion mediates phosphorylation of subunits I, IVi1 and Vb of cytochrome c oxidase. However, the mechanism of activation of the kinase under hypoxia remains unclear. It is also unclear if hypoxic stress activated PKA is different from the cAMP dependent mitochondrial PKA activity reported under normal physiological conditions. In this study using RAW 264.7 macrophages and in vitro perfused mouse heart system we investigated the nature of PKA activated under hypoxia. Limited protease treatment and digitonin fractionation of intact mitochondria suggests that higher mitochondrial PKA activity under hypoxia is mainly due to increased sequestration of PKA Catalytic α (PKAα) subunit in the mitochondrial matrix compartment. The increase in PKA activity is independent of mitochondrial cAMP and is not inhibited by adenylate cyclase inhibitor, KH7. Instead, activation of hypoxia-induced PKA is dependent on reactive oxygen species (ROS). H89, an inhibitor of PKA activity and the antioxidant Mito-CP prevented loss of CcO activity in macrophages under hypoxia and in mouse heart under ischemia/reperfusion injury. Substitution of wild type subunit Vb of CcO with phosphorylation resistant S40A mutant subunit attenuated the loss of CcO activity and reduced ROS production. These results provide a compelling evidence for hypoxia induced phosphorylation as a signal for CcO dysfunction. The results also describe a novel mechanism of mitochondrial PKA activation which is independent of mitochondrial cAMP, but responsive to ROS.
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Di Benedetto G, Scalzotto E, Mongillo M, Pozzan T. Mitochondrial Ca²⁺ uptake induces cyclic AMP generation in the matrix and modulates organelle ATP levels. Cell Metab 2013; 17:965-975. [PMID: 23747252 DOI: 10.1016/j.cmet.2013.05.003] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 03/08/2013] [Accepted: 04/08/2013] [Indexed: 01/09/2023]
Abstract
While the role of mitochondrial Ca²⁺ homeostasis in cell pathophysiology is widely accepted, the possibility that cAMP regulates mitochondrial functions has only recently received experimental support. The site of cAMP production, its targets, and its functions in the organelles remain uncertain. Using a variety of genetic/pharmacological tools, we here demonstrate that the mitochondrial inner membrane is impermeable to cytosolic cAMP, while an autonomous cAMP signaling toolkit is expressed in the matrix. We demonstrate that rises in matrix Ca²⁺ powerfully stimulate cAMP increases within mitochondria and that matrix cAMP levels regulate their ATP synthesizing efficiency. In cardiomyocyte cultures, mitochondrial cAMP can be increased by treatments that augment the frequency and amplitude of Ca²⁺ oscillations within the cytosol and organelles, revealing that mitochondria can integrate an oscillatory Ca²⁺ signal to increase cAMP in their matrix. The present data reveal the existence, within mitochondria, of a hitherto unknown crosstalk between Ca²⁺ and cAMP.
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Affiliation(s)
- Giulietta Di Benedetto
- Institute of Neuroscience, Italian National Research Council (CNR), Viale G. Colombo 3, 35121 Padova, Italy; Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy.
| | - Elisa Scalzotto
- Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
| | - Marco Mongillo
- Institute of Neuroscience, Italian National Research Council (CNR), Viale G. Colombo 3, 35121 Padova, Italy; Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| | - Tullio Pozzan
- Institute of Neuroscience, Italian National Research Council (CNR), Viale G. Colombo 3, 35121 Padova, Italy; Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
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Abstract
Phosphorylation of mitochondrial proteins has emerged as a major regulatory mechanism for metabolic adaptation. cAMP signaling and PKA phosphorylation of mitochondrial proteins have just started to be investigated, and the presence of cAMP-generating enzymes and PKA inside mitochondria is still controversial. Here, we discuss the role of cAMP in regulating mitochondrial bioenergetics through protein phosphorylation and the evidence for soluble adenylyl cyclase as the source of cAMP inside mitochondria.
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Affiliation(s)
- Federica Valsecchi
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, USA
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24
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Probes of the mitochondrial cAMP-dependent protein kinase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1359-63. [PMID: 23410952 DOI: 10.1016/j.bbapap.2013.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 02/02/2013] [Accepted: 02/02/2013] [Indexed: 11/22/2022]
Abstract
The development of a fluorescent assay to detect activity of the mitochondrial cAMP-dependent protein kinase (PKA) is described. A peptide-based sensor was utilized to quantify the relative amount of PKA activity present in each compartment of the mitochondria (the outer membrane, the intermembrane space, and the matrix). In the process of validating this assay, we discovered that PKA activity is regulated by the protease calpain. Upon exposure of bovine heart mitochondria to digitonin, Ca(2+), and a variety of electron transport chain inhibitors, the regulatory subunits of the PKA holoenzyme (R2C2) are digested, releasing active catalytic subunits. This proteolysis is attenuated by calpain inhibitor I (ALLN). This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).
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Covian R, Balaban RS. Cardiac mitochondrial matrix and respiratory complex protein phosphorylation. Am J Physiol Heart Circ Physiol 2012; 303:H940-66. [PMID: 22886415 DOI: 10.1152/ajpheart.00077.2012] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
It has become appreciated over the last several years that protein phosphorylation within the cardiac mitochondrial matrix and respiratory complexes is extensive. Given the importance of oxidative phosphorylation and the balance of energy metabolism in the heart, the potential regulatory effect of these classical signaling events on mitochondrial function is of interest. However, the functional impact of protein phosphorylation and the kinase/phosphatase system responsible for it are relatively unknown. Exceptions include the well-characterized pyruvate dehydrogenase and branched chain α-ketoacid dehydrogenase regulatory system. The first task of this review is to update the current status of protein phosphorylation detection primarily in the matrix and evaluate evidence linking these events with enzymatic function or protein processing. To manage the scope of this effort, we have focused on the pathways involved in energy metabolism. The high sensitivity of modern methods of detecting protein phosphorylation and the low specificity of many kinases suggests that detection of protein phosphorylation sites without information on the mole fraction of phosphorylation is difficult to interpret, especially in metabolic enzymes, and is likely irrelevant to function. However, several systems including protein translocation, adenine nucleotide translocase, cytochrome c, and complex IV protein phosphorylation have been well correlated with enzymatic function along with the classical dehydrogenase systems. The second task is to review the current understanding of the kinase/phosphatase system within the matrix. Though it is clear that protein phosphorylation occurs within the matrix, based on (32)P incorporation and quantitative mass spectrometry measures, the kinase/phosphatase system responsible for this process is ill-defined. An argument is presented that remnants of the much more labile bacterial protein phosphoryl transfer system may be present in the matrix and that the evaluation of this possibility will require the application of approaches developed for bacterial cell signaling to the mitochondria.
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Affiliation(s)
- Raul Covian
- Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, Bethesda, Maryland 20817, USA
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26
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Oncogenic K-ras expression is associated with derangement of the cAMP/PKA pathway and forskolin-reversible alterations of mitochondrial dynamics and respiration. Oncogene 2012; 32:352-62. [PMID: 22410778 DOI: 10.1038/onc.2012.50] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Warburg effect in cancer cells has been proposed to involve several mechanisms, including adaptation to hypoxia, oncogenes activation or loss of oncosuppressors and impaired mitochondrial function. In previous papers, it has been shown that K-ras transformed mouse cells are much more sensitive as compared with normal cells to glucose withdrawal (undergoing apoptosis) and present a high glycolytic rate and a strong reduction of mitochondrial complex I. Recent observations suggest that transformed cells have a derangement in the cyclic adenosine monophosphate/cAMP-dependent protein kinase (cAMP/PKA) pathway, which is known to regulate several mitochondrial functions. Herein, the derangement of the cAMP/PKA pathway and its impact on transformation-linked changes of mitochondrial functions is investigated. Exogenous stimulation of PKA activity, achieved by forskolin treatment, protected K-ras-transformed cells from apoptosis induced by glucose deprivation, enhanced complex I activity, intracellular adenosine triphosphate (ATP) levels, mitochondrial fusion and decreased intracellular reactive oxygen species (ROS) levels. Several of these effects were almost completely prevented by inhibiting the PKA activity. Short-time treatment with compounds favoring mitochondrial fusion strongly decreased the cellular ROS levels especially in transformed cells. These findings support the notion that glucose shortage-induced apoptosis, specific of K-ras-transformed cells, is associated to a derangement of PKA signaling that leads to mitochondrial complex I decrease, reduction of ATP formation, prevalence of mitochondrial fission over fusion, and thereby opening new approaches for development of anticancer drugs.
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27
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Shell JR, Lawrence DS. Proteolytic regulation of the mitochondrial cAMP-dependent protein kinase. Biochemistry 2012; 51:2258-64. [PMID: 22385295 DOI: 10.1021/bi201573k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The mitochondrial cAMP-dependent protein kinase (PKA) is activatable in a cAMP-independent fashion. The regulatory (R) subunits of the PKA holoenzyme (R(2)C(2)), but not the catalytic (C) subunits, suffer proteolysis upon exposure of bovine heart mitochondria to digitonin, Ca(2+), and a myriad of electron transport inhibitors. Selective loss of both the RI- and RII-type subunits was demonstrated via Western blot analysis, and activation of the C subunit was revealed by phosphorylation of a validated PKA peptide substrate. Selective proteolysis transpires in a calpain-dependent fashion as demonstrated by exposure of the R and C subunits of PKA to calpain and by attenuation of R and C subunit proteolysis in the presence of calpain inhibitor I. By contrast, exposure of mitochondria to cAMP fails to promote R subunit degradation, although it does result in enhanced C subunit catalytic activity. Treatment of mitochondria with electron transport chain inhibitors rotenone, antimycin A, sodium azide, and oligomycin, as well as an uncoupler of oxidative phosphorylation, also elicits enhanced C subunit activity. These results are consistent with the notion that signals, originating from cAMP-independent sources, elicit enhanced mitochondrial PKA activity.
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Affiliation(s)
- Jennifer R Shell
- Departments of Chemistry, Chemical Biology and Medicinal Chemistry, and Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, United States
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28
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O'Rourke B, Van Eyk JE, Foster DB. Mitochondrial protein phosphorylation as a regulatory modality: implications for mitochondrial dysfunction in heart failure. CONGESTIVE HEART FAILURE (GREENWICH, CONN.) 2011; 17:269-82. [PMID: 22103918 PMCID: PMC4067253 DOI: 10.1111/j.1751-7133.2011.00266.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Phosphorylation of mitochondrial proteins has been recognized for decades, and the regulation of pyruvate- and branched-chain α-ketoacid dehydrogenases by an atypical kinase/phosphatase cascade is well established. More recently, the development of new mass spectrometry-based technologies has led to the discovery of many novel phosphorylation sites on a variety of mitochondrial targets. The evidence suggests that the major classes of kinase and several phosphatases may be present at the mitochondrial outer membrane, intermembrane space, inner membrane, and matrix, but many questions remain to be answered as to the location, timing, and reversibility of these phosphorylation events and whether they are functionally relevant. The authors review phosphorylation as a mitochondrial regulatory strategy and highlight its possible role in the pathophysiology of cardiac hypertrophy and failure.
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Affiliation(s)
- Brian O'Rourke
- Department of Medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, MD 21205-2195, USA.
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Cardiac mitochondria in heart failure: normal cardiolipin profile and increased threonine phosphorylation of complex IV. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1373-82. [PMID: 21320465 DOI: 10.1016/j.bbabio.2011.02.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 02/03/2011] [Accepted: 02/05/2011] [Indexed: 11/23/2022]
Abstract
Mitochondrial dysfunction is a major contributor in heart failure (HF). We investigated whether the decrease in respirasome organization reported by us previously in cardiac mitochondria in HF is due to changes in the phospholipids of the mitochondrial inner membrane or modifications of the subunits of the electron transport chain (ETC) complexes. The contents of the main phospholipid species, including cardiolipin, as well as the molecular species of cardiolipin were unchanged in cardiac mitochondria in HF. Oxidized cardiolipin molecular species were not observed. In heart mitochondria isolated from HF, complex IV not incorporated into respirasomes exhibits increased threonine phosphorylation. Since HF is associated with increased adrenergic drive to cardiomyocytes, this increased protein phosphorylation might be explained by the involvement of cAMP-activated protein kinase. Does the preservation of cAMP-induced phosphorylation changes of mitochondrial proteins or the addition of exogenous cAMP have similar effects on oxidative phosphorylation? The usage of phosphatase inhibitors revealed a specific decrease in complex I-supported respiration with glutamate. In saponin-permeabilized cardiac fibers, pre-incubation with cAMP decreases oxidative phosphorylation due to a defect localized at complex IV of the ETC inter alia. We propose that phosphorylation of specific complex IV subunits decreases oxidative phosphorylation either by limiting the incorporation of complex IV in supercomplexes or by decreasing supercomplex stability.
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Abstract
This review focuses on the evidence accumulated in humans and animal models to the effect that mitochondria are key players in the progression of heart failure (HF). Mitochondria are the primary source of energy in the form of adenosine triphosphate that fuels the contractile apparatus, and are thus essential for the pumping activity of the heart. We evaluate changes in mitochondrial morphology and alterations in the main components of mitochondrial energetics, such as substrate utilization and oxidative phosphorylation coupled with the level of respirasomes, in the context of their contribution to the chronic energy deficit and mechanical dysfunction in HF.
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Affiliation(s)
- Mariana G Rosca
- Center for Mitochondrial Diseases, Case Western Reserve University, Cleveland, OH, USA
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31
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Agnes RS, Jernigan F, Shell JR, Sharma V, Lawrence DS. Suborganelle sensing of mitochondrial cAMP-dependent protein kinase activity. J Am Chem Soc 2010; 132:6075-80. [PMID: 20380406 DOI: 10.1021/ja909652q] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A fluorescent sensor of protein kinase activity has been developed and used to characterize the compartmentalized location of cAMP-dependent protein kinase activity in mitochondria. The sensor functions via a phosphorylation-induced release of a quencher from a peptide-based substrate, producing a 150-fold enhancement in fluorescence. The quenching phenomenon transpires via interaction of the quencher with Arg residues positioned on the peptide substrate. Although the cAMP-dependent protein kinase is known to be present in mitochondria, the relative amount of enzyme positioned in the major compartments (outer membrane, intermembrane space, and the matrix) of the organelle is unclear. The fluorescent sensor developed in this study was used to reveal the relative matrix/intermembrane space/outer membrane (85:6:9) distribution of PKA in bovine heart mitochondria.
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Affiliation(s)
- Richard S Agnes
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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VDAC, a multi-functional mitochondrial protein regulating cell life and death. Mol Aspects Med 2010; 31:227-85. [PMID: 20346371 DOI: 10.1016/j.mam.2010.03.002] [Citation(s) in RCA: 562] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 03/17/2010] [Indexed: 01/22/2023]
Abstract
Research over the past decade has extended the prevailing view of the mitochondrion to include functions well beyond the generation of cellular energy. It is now recognized that mitochondria play a crucial role in cell signaling events, inter-organellar communication, aging, cell proliferation, diseases and cell death. Thus, mitochondria play a central role in the regulation of apoptosis (programmed cell death) and serve as the venue for cellular decisions leading to cell life or death. One of the mitochondrial proteins controlling cell life and death is the voltage-dependent anion channel (VDAC), also known as mitochondrial porin. VDAC, located in the mitochondrial outer membrane, functions as gatekeeper for the entry and exit of mitochondrial metabolites, thereby controlling cross-talk between mitochondria and the rest of the cell. VDAC is also a key player in mitochondria-mediated apoptosis. Thus, in addition to regulating the metabolic and energetic functions of mitochondria, VDAC appears to be a convergence point for a variety of cell survival and cell death signals mediated by its association with various ligands and proteins. In this article, we review what is known about the VDAC channel in terms of its structure, relevance to ATP rationing, Ca(2+) homeostasis, protection against oxidative stress, regulation of apoptosis, involvement in several diseases and its role in the action of different drugs. In light of our recent findings and the recently solved NMR- and crystallography-based 3D structures of VDAC1, the focus of this review will be on the central role of VDAC in cell life and death, addressing VDAC function in the regulation of mitochondria-mediated apoptosis with an emphasis on structure-function relations. Understanding structure-function relationships of VDAC is critical for deciphering how this channel can perform such a variety of functions, all important for cell life and death. This review also provides insight into the potential of VDAC1 as a rational target for new therapeutics.
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Acin-Perez R, Salazar E, Brosel S, Yang H, Schon EA, Manfredi G. Modulation of mitochondrial protein phosphorylation by soluble adenylyl cyclase ameliorates cytochrome oxidase defects. EMBO Mol Med 2010; 1:392-406. [PMID: 20049744 PMCID: PMC2814779 DOI: 10.1002/emmm.200900046] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Phosphorylation of respiratory chain components has emerged as a mode of regulation of mitochondrial energy metabolism, but its mechanisms are still largely unexplored. A recently discovered intramitochondrial signalling pathway links CO2 generated by the Krebs cycle with the respiratory chain, through the action of a mitochondrial soluble adenylyl cyclase (mt-sAC). Cytochrome oxidase (COX), whose deficiency causes a number of fatal metabolic disorders, is a key mitochondrial enzyme activated by mt-sAC. We have now discovered that the mt-sAC pathway modulates mitochondrial biogenesis in a reactive oxygen species dependent manner, in cultured cells and in animals with COX deficiency. We show that upregulation of mt-sAC normalizes reactive oxygen species production and mitochondrial biogenesis, thereby restoring mitochondrial function. This is the first example of manipulation of a mitochondrial signalling pathway to achieve a direct positive modulation of COX, with clear implications for the development of novel approaches to treat mitochondrial diseases.
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Affiliation(s)
- Rebeca Acin-Perez
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY, USA
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De Rasmo D, Signorile A, Roca E, Papa S. cAMP response element-binding protein (CREB) is imported into mitochondria and promotes protein synthesis. FEBS J 2009; 276:4325-33. [DOI: 10.1111/j.1742-4658.2009.07133.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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35
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Acin-Perez R, Salazar E, Kamenetsky M, Buck J, Levin LR, Manfredi G. Cyclic AMP produced inside mitochondria regulates oxidative phosphorylation. Cell Metab 2009; 9:265-76. [PMID: 19254571 PMCID: PMC2684673 DOI: 10.1016/j.cmet.2009.01.012] [Citation(s) in RCA: 374] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 10/31/2008] [Accepted: 01/29/2009] [Indexed: 11/18/2022]
Abstract
Mitochondria constantly respond to changes in substrate availability and energy utilization to maintain cellular ATP supplies, and at the same time control reactive oxygen radical (ROS) production. Reversible phosphorylation of mitochondrial proteins has been proposed to play a fundamental role in metabolic homeostasis, but very little is known about the signaling pathways involved. We show here that protein kinase A (PKA) regulates ATP production by phosphorylation of mitochondrial proteins, including subunits of cytochrome c oxidase. The cyclic AMP (cAMP), which activates mitochondrial PKA, does not originate from cytoplasmic sources but is generated within mitochondria by the carbon dioxide/bicarbonate-regulated soluble adenylyl cyclase (sAC) in response to metabolically generated carbon dioxide. We demonstrate for the first time the existence of a CO(2)-HCO(3)(-)-sAC-cAMP-PKA (mito-sAC) signaling cascade wholly contained within mitochondria, which serves as a metabolic sensor modulating ATP generation and ROS production in response to nutrient availability.
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Affiliation(s)
- Rebeca Acin-Perez
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10065, USA
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Castaldo P, Cataldi M, Magi S, Lariccia V, Arcangeli S, Amoroso S. Role of the mitochondrial sodium/calcium exchanger in neuronal physiology and in the pathogenesis of neurological diseases. Prog Neurobiol 2008; 87:58-79. [PMID: 18952141 DOI: 10.1016/j.pneurobio.2008.09.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/23/2008] [Accepted: 09/29/2008] [Indexed: 11/26/2022]
Abstract
In neurons, as in other excitable cells, mitochondria extrude Ca(2+) ions from their matrix in exchange with cytosolic Na(+) ions. This exchange is mediated by a specific transporter located in the inner mitochondrial membrane, the mitochondrial Na(+)/Ca(2+) exchanger (NCX(mito)). The stoichiometry of NCX(mito)-operated Na(+)/Ca(2+) exchange has been the subject of a long controversy, but evidence of an electrogenic 3 Na(+)/1 Ca(2+) exchange is increasing. Although the molecular identity of NCX(mito) is still undetermined, data obtained in our laboratory suggest that besides the long-sought and as yet unfound mitochondrial-specific NCX, the three isoforms of plasmamembrane NCX can contribute to NCX(mito) in neurons and astrocytes. NCX(mito) has a role in controlling neuronal Ca(2+) homeostasis and neuronal bioenergetics. Indeed, by cycling the Ca(2+) ions captured by mitochondria back to the cytosol, NCX(mito) determines a shoulder in neuronal [Ca(2+)](c) responses to neurotransmitters and depolarizing stimuli which may then outlast stimulus duration. This persistent NCX(mito)-dependent Ca(2+) release has a role in post-tetanic potentiation, a form of short-term synaptic plasticity. By controlling [Ca(2+)](m) NCX(mito) regulates the activity of the Ca(2+)-sensitive enzymes pyruvate-, alpha-ketoglutarate- and isocitrate-dehydrogenases and affects the activity of the respiratory chain. Convincing experimental evidence suggests that supraphysiological activation of NCX(mito) contributes to neuronal cell death in the ischemic brain and, in epileptic neurons coping with seizure-induced ion overload, reduces the ability to reestablish normal ionic homeostasis. These data suggest that NCX(mito) could represent an important target for the development of new neurological drugs.
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Affiliation(s)
- P Castaldo
- Department of Neuroscience, Section of Pharmacology, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Torrette di Ancona, Ancona, Italy
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37
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Regulation of mitochondrial oxidative phosphorylation through cell signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1701-20. [DOI: 10.1016/j.bbamcr.2007.10.001] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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38
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Sardanelli AM, Signorile A, Nuzzi R, Rasmo DD, Technikova-Dobrova Z, Drahota Z, Occhiello A, Pica A, Papa S. Occurrence of A-kinase anchor protein and associated cAMP-dependent protein kinase in the inner compartment of mammalian mitochondria. FEBS Lett 2006; 580:5690-6. [PMID: 16996504 DOI: 10.1016/j.febslet.2006.09.020] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Accepted: 09/06/2006] [Indexed: 11/19/2022]
Abstract
Evidence showing the existence in the inner compartment of rat-heart mitochondria of AKAP121 and associated PKA is presented. Immunoblotting analysis and trypsin digestion pattern show that 90% or more of mitochondrial C-PKA, R-PKA and AKAP121 is localized in the inner mitochondrial compartment, when prepared both from isolated mitochondria or cardiomyocyte cultures. This localization is verified by measurement of the specific catalytic activity of PKA, radiolabelling of R-PKA by (32)P-phosphorylated C-PKA and of AKAP by (32)P-phosphorylated R-PKA and electron microscopy of mitochondria exposed to gold-conjugated AKAP121 antibody.
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Affiliation(s)
- Anna Maria Sardanelli
- Department of Medical Biochemistry, Biology and Physics, University of Bari, Policlinico, Piazza Giulio Cesare 11, 70124 Bari, Italy
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39
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Salvi M, Brunati AM, Toninello A. Tyrosine phosphorylation in mitochondria: a new frontier in mitochondrial signaling. Free Radic Biol Med 2005; 38:1267-77. [PMID: 15855046 DOI: 10.1016/j.freeradbiomed.2005.02.006] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 02/01/2005] [Accepted: 02/03/2005] [Indexed: 11/25/2022]
Abstract
Mitochondria are multifunctional organelles that participate in a range of cellular processes such as energy production, proliferation, death, and senescence. The involvement of mitochondria in such distinct aspects of cell life requires the existence of an integrated system of signals that enter and exit the organelle according to the diverse needs of the cell. The recent discovery of several protein kinases and phosphatases that localize partially or predominantly inside mitochondria opens new perspectives into the regulation of these signals. This review focuses on tyrosine phosphorylation in mitochondria. A description of the protein tyrosine kinases and phosphatases which regulate this process along with the mitochondrial tyrosine-phosphorylated proteins identified to date is followed by a discussion of the possible involvement of tyrosine phosphorylation in mitochondrial signaling and future perspectives for developments in this emerging field.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Università di Padova, Istituto di Neuroscienze del CNR, Unità per lo Studio delle Biomembrane, Viale G. Colombo 3, 35121 Padua, Italy
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40
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Maj MC, Raha S, Myint T, Robinson BH. Regulation of NADH/CoQ oxidoreductase: do phosphorylation events affect activity? Protein J 2004; 23:25-32. [PMID: 15115179 DOI: 10.1023/b:jopc.0000016255.17077.2c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We had previously suggested that phosphorylation of proteins by mitochondrial kinases regulate the activity of NADH/CoQ oxidoreductase. Initial data showed that pyruvate dehydrogenase kinase (PDK) and cAMP-dependent protein kinase A (PKA) phosphorylate mitochondrial membrane proteins. Upon phosphorylation with crude PDK, mitochondria appeared to be deficient in NADH/cytochrome c reductase activity associated with increased superoxide production. Conversely, phosphorylation by PKA resulted in increased NADH/cytochrome c reductase activity and decreased superoxide formation. Current data confirms PKA involvement in regulating Complex I activity through phosphorylation of an 18 kDa subunit. Beef heart NADH/ cytochrome c reductase activity increases to 150% of control upon incubation with PKA and ATP-gamma-S. We have cloned the four human isoforms of PDK and purified beef heart Complex I. Incubation of mitochondria with PDK isoforms and ATP did not alter Complex I activity or superoxide production. Radiolabeling of mitochondria and purified Complex I with PDK failed to reveal phosphorylated proteins.
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Affiliation(s)
- Mary C Maj
- Metabolic Research Programme, The Hospital for Sick Children, 555 University Avenue, Toronto M5G 1X8, Canada
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41
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Azarashvili T, Krestinina O, Odinokova I, Evtodienko Y, Reiser G. Physiological Ca2+ level and Ca2+-induced Permeability Transition Pore control protein phosphorylation in rat brain mitochondria. Cell Calcium 2003; 34:253-9. [PMID: 12887972 DOI: 10.1016/s0143-4160(03)00107-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phosphorylation of several low molecular mass proteins (3.5, 17, 23 and 29kDa) was observed in rat brain mitochondria (RBM) at ATP concentration close to that in the mitochondrial matrix. Furthermore, regulatory effects of Ca2+ on phosphorylation of these proteins were investigated. Protein phosphorylation was found to be modulated by Ca2+ in the physiological concentration range (10(-8) to 10(-6)M free Ca2+). Incorporation of 32P from [gamma-32P]ATP into the 17kDa protein was dramatically increased within the 10(-7) to 10(-6)M free Ca2+ range, whereas an opposite effect was observed for the 3.5kDa polypeptide. Strong de-phosphorylation of the 3.5kDa polypeptide and enhanced 32P-incorporation into the 17 and 23kDa proteins were found with supra-threshold Ca2+ loads and these effects were eliminated or reduced in the presence of cyclosporin A, an inhibitor of Permeability Transition Pore (PTP) opening. In the presence of calmidazolium (Cmz), a calmodulin antagonist, enhanced levels of phosphorylation of the 17 and 3.5kDa polypeptides were observed and the 17kDa protein phosphorylation was suppressed by H-8, a protein kinase A inhibitor. It is concluded that Ca2+ in physiological concentrations, as a second messenger, can control phosphorylation of the low molecular mass phospoproteins in RBM, in addition to well known regulation of some Krebs cycle dehydrogenases by Ca2+. The protein phosphorylation was strongly dependent on the Ca2+-induced PTP opening.
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Affiliation(s)
- T Azarashvili
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, RU-142290 Pushchino, Moscow region, Russia
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42
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Calabokis M, Perez J, Bubis J, Suárez-Mata Z. Minor participation of cAMP on the protein kinase phosphorylation of mitochondrial and cytosolic fractions from Ascaris suum: a comparative study with porcine heart muscle. Comp Biochem Physiol B Biochem Mol Biol 2002; 133:405-16. [PMID: 12431408 DOI: 10.1016/s1532-0456(02)00181-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In contrast to porcine heart muscle in which cAMP effectively activated the phosphorylation of cytosolic proteins, cAMP exerted a minor effect on the phosphorylation of proteins from the soluble fraction of Ascaris suum muscle. Similarly, cAMP did not enhance the kinase activity in the mitochondrial membranes from porcine heart and A. suum, although major differences in protein phosphorylation were observed between both fractions. However, cAMP-dependent protein kinases (PKA) were evidenced in the parasitic soluble mitochondrial fraction, since the phosphorylation of histone IIA and kemptide was augmented in this fraction, in the presence of cAMP. An increase in the phosphorylation of exogenously added A. suum phosphofructokinase was also obtained when cAMP was added to the parasite soluble mitochondrial fraction. The phosphorylation of phosphofructokinase by this fraction was inhibited when kemptide and cAMP were included in the reaction mixture, suggesting substrate competition for the same PKA. Although PKI (6-22), a reported inhibitor of the catalytic subunit of mammalian cAMP-dependent PKAs, did not affect the endogenous phosphorylation of proteins in the various A. suum fractions, an inhibition on the phosphorylation of exogenously added kemptide and phosphofructokinase was observed when PKI (6-22) was incubated with the parasite mitochondrial soluble fraction.
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Affiliation(s)
- Maritza Calabokis
- Departamento de Biología Celular, División de Ciencias Biológicas, Universidad Simón Bolivar, Apartado 89.000, Caracas 1081-A, Venezuela.
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43
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Azarashvili TS, Tyynelä J, Odinokova IV, Grigorjev PA, Baumann M, Evtodienko YV, Saris NEL. Phosphorylation of a peptide related to subunit c of the F0F1-ATPase/ATP synthase and relationship to permeability transition pore opening in mitochondria. J Bioenerg Biomembr 2002; 34:279-84. [PMID: 12392191 DOI: 10.1023/a:1020204518513] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A phosphorylated polypeptide (ScIRP) from the inner membrane of rat liver mitochondria with an apparent molecular mass of 3.5 kDa was found to be immunoreactive with specific antibodies against subunit c of F0F1-ATPase/ATP synthase (Azarashvily, T. S., Tyynelä, J., Baumann, M., Evtodienko, Yu. V., and Saris, N.-E. L. (2000). Biochem. Biophys. Res. Commun. 270, 741-744. In the present paper we show that the dephosphorylation of ScIRP was promoted by the Ca2+-induced mitochondrial permeability transition (MPT) and prevented by cyclosporin A. Preincubation of ScIRP isolated in its dephosphorylated form with the mitochondrial suspension decreased the membrane potential (delta psiM) and the Ca2+-uptake capacity by promoting MPT. Incorporation of ScIRP into black-lipid membranes increased the membrane conductivity by inducing channel formation that was also suppressed by antibodies to subunit c. These data indicate that the phosphorylation level of ScIRP is influenced by the MPT pore state, presumably by stimulation of calcineurin phosphatase by the Ca2+ used to induce MPT. The possibility of ScIRP being part of the MPT pore assembly is discussed in view of its capability to induced channel activity.
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Affiliation(s)
- Tamara S Azarashvili
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region
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44
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Technikova-Dobrova Z, Sardanelli AM, Speranza F, Scacco S, Signorile A, Lorusso V, Papa S. Cyclic adenosine monophosphate-dependent phosphorylation of mammalian mitochondrial proteins: enzyme and substrate characterization and functional role. Biochemistry 2001; 40:13941-7. [PMID: 11705384 DOI: 10.1021/bi011066p] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A study is presented on cyclic adenosine monophosphate- (cAMP-) dependent phosphorylation of mammalian mitochondrial proteins. Immunodetection with specific antibodies reveals the presence of the catalytic and the regulatory subunits of cAMP-dependent protein kinase (PKA) in the inner membrane and matrix of bovine heart mitochondria. The mitochondrial cAMP-dependent protein kinase phosphorylates mitochondrial proteins of 29, 18, and 6.5 kDa. With added histone as substrate, PKA exhibits affinities for ATP and cAMP and pH optimum comparable to those of the cytosolic PKA. Among the mitochondrial proteins phosphorylated by PKA, one is the nuclear-encoded (NDUFS4 gene) 18 kDa subunit of complex I, which has phosphorylation consensus sites in the C terminus and in the presequence. cAMP promotes phosphorylation of the 18 kDa subunit of complex I in myoblasts in culture and in their isolated mitoplast fraction. In both cases cAMP-dependent phosphorylation of the 18 kDa subunit of complex I is accompanied by enhancement of the activity of the complex. These results, and the finding of mutations in the NDUFS4 gene in patients with complex I deficiency, provide evidence showing that cAMP-dependent phosphorylation of the 18 kDa subunit of complex I plays a major role in the control of the mitochondrial respiratory activity.
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Affiliation(s)
- Z Technikova-Dobrova
- Department of Medical Biochemistry and Biology, University of Bari, Piazza G.Cesare 70124 Bari, Italy
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45
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Kadenbach B, Hüttemann M, Arnold S, Lee I, Bender E. Mitochondrial energy metabolism is regulated via nuclear-coded subunits of cytochrome c oxidase. Free Radic Biol Med 2000; 29:211-21. [PMID: 11035249 DOI: 10.1016/s0891-5849(00)00305-1] [Citation(s) in RCA: 197] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A new mechanism on regulation of mitochondrial energy metabolism is proposed on the basis of reversible control of respiration by the intramitochondrial ATP/ADP ratio and slip of proton pumping (decreased H+/e- stoichiometry) in cytochrome c oxidase (COX) at high proton motive force delta p. cAMP-dependent phosphorylation of COX switches on and Ca2+-dependent dephosphorylation switches off the allosteric ATP-inhibition of COX (nucleotides bind to subunit IV). Control of respiration via phosphorylated COX by the ATP/ADP ratio keeps delta p (mainly delta psi(m)) low. Hormone induced Ca2+-dependent dephosphorylation results in loss of ATP-inhibition, increase of respiration and delta p with consequent slip in proton pumping. Slip in COX increases the free energy of reaction, resulting in increased rates of respiration, thermogenesis and ATP-synthesis. Increased delta psi(m) stimulates production of reactive oxygen species (ROS), mutations of mitochondrial DNA and accelerates aging. Slip of proton pumping without dephosphorylation and increase of delta p is found permanently in the liver-type isozyme of COX (subunit VIaL) and at high intramitochondrial ATP/ADP ratios in the heart-type isozyme (subunit VIaH). High substrate pressure (sigmoidal v/s kinetics), palmitate and 3,5-diiodothyronine (binding to subunit Va) increase also delta p, ROS production and slip but without dephosphorylation of COX.
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Affiliation(s)
- B Kadenbach
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
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46
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Scacco S, Vergari R, Scarpulla RC, Technikova-Dobrova Z, Sardanelli A, Lambo R, Lorusso V, Papa S. cAMP-dependent phosphorylation of the nuclear encoded 18-kDa (IP) subunit of respiratory complex I and activation of the complex in serum-starved mouse fibroblast cultures. J Biol Chem 2000; 275:17578-82. [PMID: 10747996 DOI: 10.1074/jbc.m001174200] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A study is presented on the in vivo effect of elevated cAMP levels induced by cholera toxin on the phosphorylation of subunits of the mitochondrial respiratory complexes and their activities in Balb/c 3T3 mouse fibroblast cultures. Treatment of serum-starved fibroblasts with cholera toxin promoted serine phosphorylation in the 18-kDa subunit of complex I. Phosphorylation of the 18-kDa subunit, in response to cholera toxin treatment of fibroblasts, was accompanied by a 2-3-fold enhancement of the rotenone-sensitive endogenous respiration of fibroblasts, of the rotenone-sensitive NADH oxidase, and of the NADH:ubiquinone oxidoreductase activity of complex I. Direct exposure of fibroblasts to dibutyryl cAMP resulted in an equally potent stimulation of the NADH:ubiquinone oxidoreductase activity. Stimulation of complex I activity and respiration with NAD-linked substrates were also observed upon short incubation of isolated fibroblast mitoplasts with dibutyryl cAMP and ATP, which also promoted phosphorylation of the 18-kDa subunit. These observations document an extension of cAMP-mediated intracellular signal transduction to the regulation of cellular respiration.
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Affiliation(s)
- S Scacco
- Department of Cell and Molecular Biology, Northwestern Medical School, Chicago, Illinois 60611, USA
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47
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Azarashvily TS, Tyynelä J, Baumann M, Evtodienko YV, Saris NE. Ca(2+)-modulated phosphorylation of a low-molecular-mass polypeptide in rat liver mitochondria: evidence that it is identical with subunit c of F(0)F(1)-ATPase. Biochem Biophys Res Commun 2000; 270:741-4. [PMID: 10772894 DOI: 10.1006/bbrc.2000.2488] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A 3.5-kDa polypeptide associated with the inner membrane of rat liver was found to be phosphorylated by [gamma-(32)P]ATP, presumably via a cAMP-dependent kinase. The phosphorylation was modulated by [Ca(2+)] in the physiological range, with a minimum at 1 microM and rising fourfold toward lower (10 nM) and higher (10 microM) concentrations. Further characterization of the 3.5-kDa component showed that the polypeptide has the same electrophoretic mobility as subunit c of F(0)F(1)-ATPase and that it selectively binds to antibodies against subunit c.
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Affiliation(s)
- T S Azarashvily
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, RU-142292, Russia
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48
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Bender E, Kadenbach B. The allosteric ATP-inhibition of cytochrome c oxidase activity is reversibly switched on by cAMP-dependent phosphorylation. FEBS Lett 2000; 466:130-4. [PMID: 10648827 DOI: 10.1016/s0014-5793(99)01773-1] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In previous studies the allosteric inhibition of cytochrome c oxidase at high intramitochondrial ATP/ADP-ratios via binding of the nucleotides to the matrix domain of subunit IV was demonstrated. Here we show that the allosteric ATP-inhibition of the isolated bovine heart enzyme is switched on by cAMP-dependent phosphorylation with protein kinase A of subunits II (and/or III) and Vb, and switched off by subsequent incubation with protein phosphatase 1. It is suggested that after cAMP-dependent phosphorylation of cytochrome c oxidase mitochondrial respiration is controlled by the ATP/ADP-ratio keeping the proton motive force Deltap low, and the efficiency of energy transduction high. After Ca(2+)-induced dephosphorylation this control is lost, accompanied by increase of Deltap, slip of proton pumping (decreased H(+)/e(-) stoichiometry), and increase of the rate of respiration and ATP-synthesis at a decreased efficiency of energy transduction.
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Affiliation(s)
- E Bender
- Fachbereich Chemie, Philipps-Universität, D-35032, Marburg, Germany
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49
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Papa S, Sardanelli AM, Scacco S, Technikova-Dobrova Z. cAMP-dependent protein kinase and phosphoproteins in mammalian mitochondria. An extension of the cAMP-mediated intracellular signal transduction. FEBS Lett 1999; 444:245-9. [PMID: 10050768 DOI: 10.1016/s0014-5793(99)00070-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Evidence has been obtained for the occurrence of a cAMP-dependent serine protein kinase associated with the inner membrane/matrix of mammalian mitochondria. The catalytic site of this kinase is localized at the inner side of the inner membrane, where it phosphorylates a number of mitochondrial proteins. One of these has been identified as the AQDQ subunit of complex I. cAMP-dependent phosphorylation of this protein promotes the activity of complex I and mitochondrial respiration. A 5 bp duplication in the nuclear gene encoding this protein has been found in a human patient, which eliminates the phosphorylation site. PKA anchoring proteins have recently been identified in the outer membrane of mammalian mitochondria, which could direct phosphorylation of proteins at contact sites with other cell structures.
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Affiliation(s)
- S Papa
- Institute of Medical Biochemistry and Chemistry University of Bari, Policlinico, Italy.
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50
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Yang WL, Iacono L, Tang WM, Chin KV. Novel function of the regulatory subunit of protein kinase A: regulation of cytochrome c oxidase activity and cytochrome c release. Biochemistry 1998; 37:14175-80. [PMID: 9760254 DOI: 10.1021/bi981402a] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
There have been speculations that the regulatory (R) subunit of the cAMP-dependent protein kinase (PKA) may have other functions. A recent study has shown that the catalytic (C) subunit of PKA may be regulated in a cAMP- and R subunit-independent manner. However, evidence linking a function to the R subunit apart from inhibiting the C subunit has been elusive. In this report, interaction cloning experiments showed that the RIalpha subunit association with the cytochrome c oxidase subunit Vb (CoxVb) is cAMP-sensitive. Interaction was detected with a GST-RIalpha fusion protein as well as by coimmunoprecipitation. Transient treatment with cAMP-elevating agents inhibited cytochrome c oxidase in Chinese hamster ovary (CHO) cells with a concomitant decrease in cytochrome c levels in the mitochondria and an increase in its release into the cytosol. Furthermore, mutant cells harboring a defective RIalpha show increased cytochrome c oxidase activity and also constitutively lower levels of cytochrome c in comparison to either the wild-type cells or the C subunit mutant. These results suggest a novel mechanism of cAMP signaling through the interaction of RIalpha with CoxVb thereby regulating cytochrome c oxidase activity as well as the cytochrome c levels.
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Affiliation(s)
- W L Yang
- Department of Medicine and Pharmacology, Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901, USA
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